Synthesis, morphology and optical properties of pure and Eu³⁺ doped β-Ga₂O₃ hollow nanostructures by hydrothermal method

Pure and Eu³⁺ doped β-Ga₂O₃ hollow nanostructures were synthesized by hydrothermal and calcination processes using carbon spheres as templates in ethanol-water solution. Field-emission scanning electron microscopy and high-resolution transmission electron microscopy analysis revealed β-Ga₂O₃ hollow nanostructures with diameters of approximately 200 nm and shell thickness of about 20 nm. The X-ray diffraction analysis revealed that the carbon@Ga(OH)CO₃ core-shell nanostructures were in amorphous phase before calcination. After calcination, the amorphous core-shell structures yielded highly crystalline β-Ga ₂O₃ hollow nanostructures with spherical shape. The presence of the Ga(OH)CO₃ in the shell components is confirmed by the Fourier transform infrared spectrum. The Eu³⁺ doped β-Ga ₂O₃ hollow nanostructures showed strong red emission corresponding to the ⁵D₄ → ⁷F_J transition.